Method and apparatus for diverting animal forms of life



Aug. 5, 1952 H. 1'. BURKEY 2,605,742

' .METHOD AND APPARATUS FOR DIVERTING ANIMAL FORMS OF LIFE F116;; Feb. 9', 1945 2 SHEETS-Sl-IEET 1 MHGNET/C cox/puns COUPLING HEA/Ef r.

Patented Aug. 5, 1952 UNITED l STAT METHOD AND APPARATUS FOR. DIVERTING ANIMAL FORMS OF LIFE Henry 'rnurkoy, Hollywood, Calif. Application February 9, 1945,. Serial No. 577,080

1 Claim. (01. 119-2) My invention relates to a method and apparatus for electrically charging a zone of Water to divert, control and/or conserve animal forms of life, as

v distinguished from vegetation. Such zones are- I. generally electrically charged water for use with fish, aquatic'mammals, star fish, water fowl,

teredos and like marine worms and insects, which in certain stages of their life cycle inhabit water. My invention also includes charging certain somewhat solid materials having a Water or electrolyte component, with an appreciable electrical load resistance. Thus some rodents and other land dwelling animals may be controlled as noted in the detailed description.

My present invention relates to improvements in the methods and apparatus developed in my United States patents 1,269,380 of June 11, 1918;, 1,292,246 of January 21, 1919; 1,515,547 of November 11, 1924; 1,882,482 of October 11, 1932, and 1,974,444 of September 25, 1934.

A phase of my present invention relates to the commercial economy and lower cost of the electric current used, together with charging water zones of much larger'volume. This is accom- 'plished by use of intermittent peaked electrical Waves of increased voltage and amperage. Where such type of electrical wave form is used the time period between individual peaks is adjusted and maintained to prevent physiological tetanus and provideperiods of relief from shock as described in my' Patent 1,974,444, when it is desired to control and conserve aquatic life.

, For the immediate, above noted purpose I have developed an electrical wave form with peaks of short time duration compared with the effective time of wave cycle and the time period of low or no current fiow. The wave form may be unidirectional, i. e., in one direction or bidirectional,

i. e., ofalt'ernating or reverse polarity. I have developed apparatus and methods of obtaining the desired wave form by capacitor discharge into the water zone. The capacitor discharge may be controlled electronically or mechanically. I also produce a suitable electrical wave form by'the use of an impulse or peaking type of transformer energized with a low frequency A. C. source of power or interrupted D. C. I

In my invention I electrically energize a water zone of moderate electrical resistance. When the peaked wave is obtained by a capacitor discharge, such discharge is almost instantaneous. In' a water zone of high mineral content, as sea water, which has much lowerelectrical-resistance than fresh water, the capacitorcontrol is adjusted and to bleed the current fiow gradually into the water. In a fresh water zone the control of the electrical wave must be adjusted and maintained toalso produce individual sharp peaks, spaced by time periods of no or negligible current fiow.

Due to the relatively short time period of the individual, peak portion of the electrical wave,

than formerly and this with economy of total wattage consumption. For example, in accordance with the teachings of the present invention the electrical wave is of shortest possible duration and in certain installations of the type described herein the peak voltage applied may be of the order of 800 volts at a rate of four to eight impulses per second, the peak current flow being amperes. when the resistance of the component water zone is ten ohms. Even with unidirectional current fiow'there is negligible electrolytic action on the electrodes, even in sea or other mineral containing waters.

The electrical shock to fish is greater when the flow of electric current is lengthwise of the fish than when crosswise through the body. The reason for this appears to be that the body structure of the fish is a better electrical conductor than the volume of water displaced. Due to the conductivity of fish being greater than the water displaced, the current in such space follows the path of least electrical resistance, which is lengthwise through the fish. In a specific electrified zone when a large fish enters such zone it feels and reacts to the shock before a smaller fish entering the same zone. This is apparently due to the greater surface contact and larger body volume of the large relative to the small fish.

Hence with my improved electrification of the water zone I am less dependent on the electric current and flow of water being in the same direction, as described in my Patent 1,882,482. My improved wave form, with increased voltage and amperage makes possible the charging of a larger zone of water and hence subjects fish to shock in localities where the direction of water fiow is immaterial. When water flow is swift fish usually are carried with the water or swim against the now. My improved electrified zone may be used to shock fish, and yet let them swim outside of the highly charged zonebefore the force of water flow carries them too deeply into the charged zone or past the fish diverter. This conduces to conservation of fish life. In most places where fish diverters are installed the line of travel of such fish may be determined and pairs of electrodes or electrode and ground 4 be immersed in water and both electrically grounded and displaced one from the other.

My theory is that when both electrode are grounded a portion of the current is by-passed through the ground between the electrodes, but

that sufficient current passes through the water lVhere only to stop or divert fish and the like. I one electrode is grounded the eff ect is much the same; Where both electrodes areinsulated from the ground and" disposed in thefwater most of the current flow is usually through the water.

by an electronic grid controlled tube such as a Thyratron. The Thyratron tube may beilofv the? General Electric type FG57 or one of the West- "The electrical current action or eiiect in water in proximity to one or both of the immersed electrodes is due to the relatively high voltage inghouse types WLSSI, or KU628, while the igni tron type of tube may be oifwjestinghouse type WLSBl/GSS. With suitable electrical connections H uses as a source'the common 110 volt A.-C. service,

transformed to suitable higher vo1tage, rectified to uni-directional current, which charges the capacitor. The capacitor discharge to load, i. e., water, is through an electronic relay "of the Thyratron type, the grid of which is maintained ata suitable bias by a potential source such as a C-battery or A; C. suitably rectified and adjusted bya potentiometer.

A simple capacitor discharge, uses D. C. to charge the capacitor, which is intermittently discharged mechanically into the water load. For instance a hand operated generator, for a second or Sobhargsthe capacitor andby a suitable circuit closer causes a practically"instantaneous capacitor'discharge. I

The impulse or peaking transformer uses a suitable low frequency source of power, a step up transformer,- the secondary of which is connecte-dto the load. This provides a Water zone charged alternately positive and negative with'a sharpl peaked Wave, with a considerable time period between the peaks.

My electrical control equipment provides for a ready change from physiological non-tetanizing to tetanizing water zones. When the frequency'of discharge to load is increased, without anychange in wave form, the accumulative efiect becomes more severe. This as to] fish, teredo worms, aquatic fowls and'like is appar-- ently duefto causing physiological tetanus, as noted in my Patent 1,974,444, mentioned above.

My pr'esent development of the wave form characterized by a steep or peaked wave of much highcrvoltage than formerly, enables me to dispense withinsulating either-or both electrodes. In such'case as explained previously, the peak waves are of shortest possible duration, recurring four to eight times per second and having, for example, a peak voltage of 800 volts. I may have both) electrodes electrically grounded-and positioned remote from each other'at a much greater distance than the space of water which carries an electrical charge of sufiicient strength to causefish to avoid such space. For instance one electrodemay be immersed in water and the other embedded in earth or soil a relatively small distance from the body of Water. Again both electrodes may be installed in the water,fone for both insulated electrically from the ground, "a'nd remote one from the other. Both'electrodesmay impulse timing and current density resulting from the application of relatively highvoltages of relatively short durationin accordance with the teachings of the present invention. In such case an electric field isset up of such magnitude in regions or zones removed from the immediate vicinity of the space between electrodes to thereby produce an appreciable "efiect on animal forms' 'of life, suchas fish, in such-removed regions or zones. Fish and the like are deterred from enteringor remaining in such higher electrified zone or region removed from the immediate space adjacent electrodes. I I 1 Electric current in a water zone, between two electrodes of different potential, or between one electrode in the zone and a remote ground tends totravel the path of greatest electrical conductivity; However with my individual peaked type of electrical wave and almost instantaneous discharge to the Water zone load, there is electrical current how in the zone space in addition to the current flowx'in' the path of greatest electrical conductivity. 1 t 4 Theenergi'zed zone in proximity to the energized electrode appears to spread from such electrode. Hence there "is electrical current flow through the body-of fishor aquatic animals even though such fish or aquatic animals be outside of the path of greatest electrical conductivity between the electrodes of differingpotential; My improved electrical wave form of a sharply peaked high intensity voltage in a sequence of individual peaks producesa greater expanse of'electrically energized volume of water than in'the former practice, I lence fish and aquatic animals are subject to the -'electricalshock,when at greater distances irom an energized electrode than in former p'roce'duresi This .resu-lts, for instance, in a certain volume of water, a larger proportion ofthe fish or aquatic animals receiving the electrical shock lengthwise through the body than with former methods an'd'apparatus. Therefore due to the spread condition of electrical current flow in' the water zone the diverting action on fish or aquatic animals is more pronounced, at less co st in power, than the former procedure. In my present improved practice the electric current flow in the energized Water zone is indirectionsadditional tothe path of greatest electrical conductivity between two electrodes of different pO n a-L I Mytype' of water electrode equipment varies as to the kind of nsnwater fowl, insect or Worm life tobeco ntrolled, andthetype of wave form and'frequency also varies accordingly In the control of fish the electrodes; are usuallysriispendedQin' pr immersed to the desired depth 'in the water. [Water iowl'rnay usually be kept out of designated jareasiby electrode systems carried by'flo'atsnear, the surface. "The caddis-fiy larvae are usually killed or" loosened from the "surface face electrodes the frictionto; water fiow i not :increased. Teredoes zand other aquatic worms are prevented from infestingiunder water wood structures-,by. electrodes on the surface of such structures- In my present inVe lti0n,-,inmanyinstances, I make usepf some butnot all equipment commonly usedor installed.- Water diversion flumes, intakes-to municipalwater services, etc. are now commonly provided with trash racks or screens at; the intake. With my invention fishmay be kept at such a distance from the trash racksor screens that the water flow will not suck and. hold themagainst the rack or screens. Without the use of :my equipment diverted water and domestic water... frequently becomes contaminatedv lwith decomposed fish held against trash racks, or screensby force of water-flow; As the present trashlracks and screens usually makea good electrical ground I make use of the same. In thisr latter case my energizedi. e.', insulated electrodes are 1 usually spaced 2. distance from the trashracks or water screens, When energized the electrified zone extends in greatest strength between the electrodes and the grounded trash racks or screens and in lesser strength outwardly beyond theenergized electrodes.

Where electrodes alone are used these are ar ranged connected in a desired sequence to opposite electrical leads from the control discharge equipment. This arrangement with consecutive electrodes of opposite-polarity produces overlapping zones of water electricallycharged, during the current flow. Withflush surface electrodes 8 it is usually desirable to have: consecutive ele'c trodes ofop'po'sit'e pctential. I also employ improved equipment of a' g'rounded electrode,

usually on'th'e bottom ofbody of water, with 'suspendedmrwall attached energized electrodes. As both the energized-L el,-insul ated electrodes and the grounded electrodes causean energized zone beyond the electrode line the energized electrodes may, when necessary be located down stream from the trash rack. This is usually'only necessary when the trash rackscan' have no obstruction to navigation, floating -logs, etc.

My invention is illustrated in connection with the accompanying drawings, in which:

I 6 tea w rmed. ia ee s e i h; c a e: tures of the present invention-1:,

FigQJ'Y ilI strates an ins lat'edflelectrode grid, with agrounded screen'in proxi'mity'to a saucer valye water inlet in accordance with certain: features of thepresent invention. I

In Figurelpower is supplied'from a three phase circuit 1, 2, 3 to a three phase transformer 4 having a delta connected primary winding 5 and a star connected secondary winding 6. The high voltage current obtained from the secondary winding, this rectified by three phase, half wave rectifiertubeslfi, 9 and charge a bank of capacitors Ill- When the charge voltage across-the capacitor bank [-0 reaches its adjustable, preset, value, 'as determined by potentiometer II the bias on the, control gridof Thyratron tube [2 causes, this -';I,hyratron tube (2 to ignite the series electronic relayignitron type tube I3,; discharging the stored energy from the capacitors into thewater load circuit 14. v

, At the instant of igniting the series ignitron tube I3'the current flowing through thefiring Thyratron tube IZcauses avoltage dropto appearacrossan impulse transformer 15, .This impulse is used to cause Thyratron tube l6 to block the main rectifier tubes 1,- 8 and 9 during theperiod of discharging capacitor bank I 0. v The blocking time and consequently the rate *ofop- ,eration. is made. adjustable by altering the rate of charging aj capacitor l'ljin the grid circuit of Thyratron tubev l8. Thyratron tube l8 unblocks themain rectifier tubes I, 8 and 9 and automatically sets up the sequence circuit for causing Thyratron tube l6to again block the main rectifier tubes 1, 8 and 9 during the next operating cycle. This feature automatically clearsvfaulty operation of the discharge circuit, between the capacitor bank ill and the water load circuit". A potentiometer adjustment I9 is provided for varying the blocking time of the main rectifier tubes 1, 8 and 9 and consequently the rate of Fig. 1 shows an electrical diagram of circuits, j

with symbols, for a 3 phase A. C. supply using electroniecontrolled capacitor discharge in accordance with the present invention.

Fig.2 is an electrical diagram of a powerunit having single phase A. C. supply, electronic controlled capacitor discharge in accordance with the present invention. i l

Fig.3'is an'electrical diagram of a D. C. supply and capacitor discharge equipment, mechanically controlled, embodying certain features of the presentinvention.

Fig; 4 is an electrical diagram of a peaking transformer for charging water from the secondary winding thereof in accordancewith certain teachings of the present invention.

Fig. 4A shows a transformer unit connected to realize certain features of the present invention.

' Fig. 5 shows anelectrical wave form developed by use of the apparatus shownin Fig. 4.

v-F -ig. 5A. shows an electrical wa ve form developedby use of apparatus shown inFig. 4A.

Fig. 6 illustrates aninsulated electrode. grid operation of the control circuit.

Specifically, the Y-connected secondary winding 6 has its unconnected terminals connected respectively to the anode or plateof the Thyratron discharge devices 1, 8,9, the common terminal'of the secondary winding -6 being connected to one terminal of the water load circuit l4 through the ignitron device I3 while the other terminal of the water load circuit 14 is connected to the grounded cathodes of devices 1, 8 and 9. The main control grids of devices 1, 8 and 9- is each connected through currentlimiting resistances 2T, 28 and 29, respectively,to the control lead A whose potential'is important in determining the operation of devices 1, 8 and 9. Control lead A is connected to the grounded cathodes of devices 1, 8 and 9 through the serially connected resistances 4| and 40, resistances 40 and M pro-' viding an input circuit for the devices I, 8 and 9. The voltage across resistance 40 is determined by the amount of space current flowing through the blanking device 16 while the magnitude of the potential existing across resistance 4| is determined by the space current flowing through the triggering device 18. It is noted that the voltages existing across resistances 40 and 4| are of opposite polarity as indicated by the plus andminus signs in. the sense that the voltage applied between the main control grids of devices 1,8 and 9 and their common cathodes is equal to the difference in voltage existing across the resistances (HIV and 4|. It is noted further that the voltage existing across'resistance 4D has a polarity tending-tc block the now brqurrenrm tubes '1", 8-and9 while the potential existing across resistance 4! does either in factor te'nd'to cause the Thyratron Space current forj'each one of the devices "[6 and I8 is obtained from the full wave rectifier 2-l ;"-the positive output-terminal of-which is connectedto'the plates of the devices [6 and I8 while the negative terminal of the rectifier 2 lis on the one end connected to the cathode ofdev ice 16 through resistance 40 and on 'theoth'er end to fthecathode'of device 18 through the serially connected resistances M and '42;

lt isnoted that the secondary winding 15A, which is mag'neticallycou'pled tof'itsp'rim'ary winding 15, is connected between themain control grid and the cathode of-' the;device"l6 to cause the tube IG 'tofi're 'upon the transfer of an energy pulse from winding 1 due to magneticall coupled secondary winding l 5A. 7 r

The Thyratron device lfi-isso adjusted "that it does hotfire until'the nerg pulse is transmitted to --the primarywinding [5i and upon that occurrence arelativly largeamo'unt of current news through resistance 40; thereby to render the-control lead A substantially negative to cause tubes 7,8 and 9to block. l "While such relatively ia-rge amount of current flows" through resistance a 40 the potential drop thereacross'jof course is relatively large and this potential drop is applied to the main control grid of "device l8 through'resistahces 36, 46, I9 and-'44 and condenser 60. I control grid of device Hldoes not fall instantaneously. The potential'variations across resistance 40, due to the presence of the condenser 60, may be. charged at a variable rate by adjustment of 'the variable resistance 19. After a predetermined-period of time the main control "grid of device 1.8 becomes sufficiently positive due to'the relatively large positive voltage across resistance 40 and the device 18 firesthereby' to causea relatively largefspace current to'fiow' through resistance 4 I ,to makethe control lead Aof sufiicie'ntjpositive potential to allow'the devices 1, 8

' while on the other hand a similar efiect appears when device 18- is fired due to the'rectifying deviceJdA connected between the main control gridof device l8;andthe cathode of device-I6. Thus, when devices]; Band 9 are fired a relatively large energy pulse is transferred to thernain controlgrideircuitpof; device l6 through th e secondary winding IEA; thereby to cause a' large current to fiowthrough resistance '40 to render the control lead Asuficiently negative tomake devices I, 8 and Snonc nducting. This relatively large voltage acrossresistance was transferred to an integrating circuit in the grid circuitof device [8 therebyjto ,cause the "device" 118 to fire a predetermined period of time after ev ce 1 6" is fired. When device .18 is fired'th "device I 6' carries 'no appreciable fcurrent' inasmuchfas there is no energy pulse present in the secondary windinpotential between the; anode "and" cathode of It is noted that the main 8 device [6 is minimized. Consequently control lead A after device [8 is=-fired-' assumesa relatively large potential thereby to allow devices I,v

Miscellaneous'resistors and capacitors are used throughout the unitto properly balance the circuits 'and' give the necessary control as outlined above. Dry type rectifiers 20,21, 22,-23-'and' 24 are'used to supply all grid 'bias as well as plate voltage on Thyratron-tubes l6 and I8.

Certain electrical values I havefound'satisfactory with the circuits of Figure 1 and elements thereof are:

Resistors and potentiometers' in ohms 21-- 75,000; 28-'75,00'0; '29-75,000; 30-24g000; '31- 3,00'0;"322,000; 33'15;34'75,000; 35-'-.2,000; 3li'25,000; 3'I100,000;3820,000; 39-100;000; 40-3,800;4|2,000; 42'2,000; 43-5,000; 44- 100,000; 45-100,000; 46-,-2,000;' ll-Q3300; I9-- 25,000; lI--2,500. Capacitors in microfarads 50.01; 5|.01;.'52-'-.01;532.0; E i--01; 2.0; 56-002; 51 --1.-0;5810.0; 59.002; [1%.0; 602.0; 10-225, each. I

'In Figure 1 T4, TSaand T6 represent: primary windings of a power transformer while thewindings'have the-samereference numeral with the letter S added signify that-they are magnetically' coupled and form'secondary windings; for example,-T4S is a secondary winding-having-a winding T4 as a primary winding; TBS isa'secondary winding of atransformer having TGyas a primary winding 'and TSS as a secondary winding,,etc. The circuit parameters given above applywhen the a paratus is connected to a source of 60- cycles alternating voltage having-an effective value of 230volts. g v, y In Figure 2 an A. C..-single pha se source-l0 110 v.) is connected-to astep up transformer Bl, the secondary 82; being provided;with voltage settingtaps and switch 83. Thehalf-wave-rectifier 84 chargesthe capacitor 85 each half wavc cycle. The charging rate;.of;capacitor-85 is regulated by adjustablerheostat -81.

The grid controlled tube-28 0f the Thyratron type has its grid' biasfpreset by a connection 89 to one terminal of switch 83 connectedto transformer BL' Aresistoriqqfl prevents damage to tube 28;" Filaments of tubes'QBl andYR are heated by conventional insulated 'filament transformers 9| and 92, respectively. The connection fron'i the tube 84 to 'c'apacitordiby 1ead93.is from center tap of the 'se'condary or transformer 9|.

v The. grid "controlledftube 28 (Thyr'atronl prevents the capacitor 85 "from discharging through said'tube ZBHueLtdthe negative-bias on the grid of said tube. 'Wh'en' the negativefbias' is overcome tube zs nres or"passescurrent, dischargin}; icapa'oitol "85"into' the'- water load 94. Grid leak capacitor is in "the'grid to the. cathode connection of tube 28. Lead 96"connects-capaci torf85 to the anode circuit 'o f'tub' 2a. Groundingcapa'c'itor 91 is"associated"'with"'source an to prevent radio interference. Switch 98 is" held open until the .tubes 84 and 88""are' .s'u'fiiciently heated to function properly when 'under load.

'" This constructionandcircuit produces peaked type of electrical" waves infthe water lo'ad. The number of sucnpeaked type waves per minute, 1;; e; impulse frequency is determined and controlled by thefa'jdjustnient of "rheostat BT'thus regulating the. time cinterval"betw'een I impulses. The voltage of said impulses and application to the water, load 94' f fdeterinined .and'cfontrolled .by setting ofthe tap switchiah v For a* more detailed'fdescriptioniofthe operation" of the circuit 'shownin' Figure 2 attention is directed to thelfollowing. descriptio Inasmuch as device. 8.4 provides aunidirectional. conducting pathgitliel condenser 85'is charged with a unidiw rectional voltage having. a polarity indicated, the rate. .or. time or number of alternations in the source 80 required vtocharge the condenser 85;. to a predetermined unidirectional potential being determined by. the magnitudejof the adjustable resistance '8 I.

of the electrodes I00, which may be grounded, theother electrodeI'III being connected to the negative terminal of the condenser 85. The thyratron tube 28 is triggered or rendered alternatively conducting or non-conducting byconnecting its grid-to a terminal on 'the secondary winding of transformer-BI through the current limiting or protective resistance 'BILand also. by connecting such} grid to its associated cathode through condenser 95.Upon application of voltage to the circuitthus'; far described. the condenser. 85 is gradually charged until itassumes a predetermined potential, to cause the thyratron tube 28 to fire or to provide a heavy current conducting path-therethrough. Upon firing of the tube 28, a current flows from the grid to the cathode to thereby charge the condenser 05 with a unidirectional potential having a polarity indicated in Figure 2, and as a result such control grid assumes a negative potential with respect to its cathode as the condenser 85 is discharged. This negative condition of the control grid is associated with the reduction in potential of condenser 85 causes device 28 to become non-conductive. Subsequently, the charge stored in condenser 95 discharges through the serial circuit comprising resistances 90 and 81, water zone 94 and cathode of tube 28, to thereby allow the device 28 to again become conductive when the unidirectional potential across condenser 85 assumes the predetermined magnitude. Resistance 90 not only serves as a current path through which condenser 95 may be discharged at a controlled rate, but also serves to limit the flow of grid current when and as the device 23 is being fired.

Fig. 3 indicates a capacitor IOA charged by a D. C. generator IIJIA and arranged to be discharged into water load I03 by operation of the switch I02. For purposes of simplification the circuit closer is indicated as operated by a cam I04 mounted on a shaft having a gear I driven from the D. C. generator IOIA. In operation, when the circuit closer I02 is open the generator IOIA charges the capacitor I00". As the cam I04 rotates it closes the circuit closer I 02 for a short time period of the cycle causing the capacitor to discharge to water load I03. Thus, the water load I03 is periodically subjected to electric impulses directly from the capacitor IO0A, which is periodically charged with voltage from generator IOI A.

Figure 4 indicates an impulse or peaking transformer I05A, which is constructed with a core I06, having an air gap N! with a magnetic shunt I08 situated therein. The magnetic shunt I08 is of magnetizable material and serves to bridge or shunt a portion of the air gap, thereby altering I When such unidirectionalpoten-' tialfacross the terminals of'condenser 85 assumes,

thereluctance of the same. The primary winding I09 is supplied with current from a low frequency A. C. source I I 0, and the resulting voltage induced in the secondary winding III is applied to water load. II2. Such voltage applied to the water load H2 .is indicated in Figure 5, which shows .a series of positive wave peaks H3 and negative peaks II4 which are produced by operation of the peaking transformer I05A in Figure 4 having an air gap I01 and magnetic shunt I08. The shape 'of the wave shown in Figure 5 comprising theseries of peaks I I3 and H4 is approximate and the time spacing of the peaks is dependent on the frequency of the A. C. source I I 0.

form a good electrical ground, which I use.

My improved construction of electrode arrangementsare shown in a series of drawings, Figure 6, a water intake H5 is provided with a conventional trash rack or screen I I6, which is usually substantial metal structure so set up as toform a good electrical ground; My energized electrified screen III is shown as made up of a row of rigid or flexible electrical conductors II8 mounted in insulators I I9 forming aframe spaced from the trash rack I I6.

In; operation the insulated. screen II! is connected to the energized side of the electric'energizing equipment and the trash rack H6 to the oppositeside of such-a supply, 1. e., the trash rack IIB forms. an electrical ground. An electrified zone of water is thus established between the trash rack H6 and energized screen II! and extends outwardly beyond the screen II'I.

Figure '7 illustrates a common type of valve I2I as the; intake toa water tower I22 for a municipal water supply reservoir or lake in which a screen I23 serves as an ordinary protection for the intake. Usually the screen I23 and valve I2I y improved grid I24 consists of conductive hoops and stringers spaced from the screen I23 by insulators 94A and secured thereto. The grid assembly I24 and screen I23 are attached to a hoisting chain I25 with insulator I26. The conducting cable I2I attached to grid I24 is connected to one terminal of the energizing unit and the screen ground connects to the other terminal.

In operation of the structure illustrated in Figure 7 the electrically energizedgrid I24 and grounded screen I23 produce a highly electrified zone between the screen and grid and a zone of lesser strength extending beyond the grid. The fish are hence diverted before they come in contact with the screen, though water may flow at a velocity suificient to prevent fish once in contact with the screen from getting free. Hence with my protective electrical grid on the municipal intake screen,-this inlet is kept open for Water flow and there is no pollution from the decomposition of fish caught on the screen.

The impulse transformer, as indicated in Figure 4A, using stored magnetic energy may be supplied with rectified current from an A. C. source. Such rectified current may be considered to flow from a continuous current source 2 I 0 havin its terminals connected'to the primary winding of the transformer through an interrupter change theenergy'drawn from the capacitor."

Changes irrsuch; load resistance will only changethe discharge time period of the capacitor of'the energizer, This feature prevents the overload-- ing of myqcapacitor type of energizer under actual operating and field conditions. The. wattage, requirements of my capacitor type'energizer ,remains 'constant,iregardless of varying resistance of load at electrodes. This is a very important advantage under actual operating and field conditions I I V c When a water "outletoriinlet employs an 111-, vetted pipe' elbow or siphon; a. suitable fish protector may be similar to that of Figure f7 inverted." It is understood that the term' electrical impulses freeof any prolongationsthereof as usedin the present specification'and claim 'sig-- nifies electrical impulses of the shortest possible duration. Such-impulses are obtained preferably by discharging'a condenser-into the water -load circuit. through circuit connections thereto 'substantially free of vany extraneous resistance, in-

ductance :or-capacity'effects, all of which tend to prolong the period during which theco-ndenser 1 life, of the type, described herein,,in an electrified water zone defined by a pair of spaced. electrodes, the .step comprising; periodically energizing said electrodes with electrical voltage wav es ,characi terized by a-sequence of peaked electrical 'impulses, each wave rapidly increasing to a maximumand ra idlydecreasing immediately after said maximumis reachedthe resulting electrical field intensityinsaid water zone during the time eriod oisuch peaked. pulses being of sufiicient intensity to appreciably affect said animal forms of life in regions;remotely'locatedifrom the path of greatest electrical, "conductivity between said electrodes,

HENRY, T.

REFERENCES LCI'IED' The ,=-fo1lo.wing references are of record. in the,

O'IHER REFERENCES.

McMillan; Bulletin of the Bureau of-jFisher-iesi vol.X LIV;1928, volume No. 1042. 

